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Keto Diet Guide

An honest guide to the ketogenic diet: what the research actually shows, how to do it safely, what to eat, and 20 easy recipes with full nutrition worked out for you.

Taking medication for diabetes or blood pressure? Talk to your GP before starting keto. Doses often need to be reduced quickly. See Safety & kit.

What is the keto diet, in plain terms?

Normally your body runs mostly on glucose (sugar) from carbohydrates. On a ketogenic diet you cut carbs so low that your liver starts turning fat into ketones, an alternative fuel your brain and muscles can use. That state is called ketosis.

To get there, most people need to keep carbohydrates under about 20–50 g of net carbs a day. For comparison, one banana or one cup of cooked rice already contains more than 20 g.

Net carbs = total carbohydrate minus fibre. Fibre isn't digested into sugar, so it doesn't count against you.

Fat ~70% Protein ~20%
Fat 65–75%Protein 15–25%Carbs 5–10%
20–50 gnet carbs a day
0.5–3.0blood ketones (mmol/L) in ketosis
2–4 daystypical time to reach ketosis

Typical share of daily energy on a well-formulated keto diet. It varies between people and programs.

What does the research actually show?

Keto is often either overhyped or dismissed. Here's what the best available studies found, with the study type and size shown so you can judge how much weight each one deserves. Tap a topic to open it.

Strong consistent results from randomised trials Moderate good trials, some limits Mixed benefits and trade-offs Early promising but small studies
Neal et al., 2008 — The Lancet Neurology
Randomised controlled trialn = 145 children (aged 2–16)3 months

Children with frequent seizures that medication hadn't controlled. 38% of the keto group had their seizures cut by more than half, compared with 6% of the control group. 7% had more than a 90% reduction (0% of controls). The most common side effects were constipation, vomiting, low energy and hunger.

Martin-McGill et al., 2020 — Cochrane systematic review
13 randomised trialsn = 932 (711 children, 221 adults)

Children on ketogenic diets were up to three times more likely to become seizure-free, and up to six times more likely to halve their seizures. The reviewers rated the certainty as low, mainly because the trials were small.

Takeaway: a proven medical therapy for drug-resistant epilepsy. It's always run by a neurologist and dietitian, and is very different from a general "keto for weight loss" diet.
Bueno et al., 2013 — British Journal of Nutrition
Meta-analysis of 13 randomised trialsn = 1,41512 months or more

People on very-low-carb keto diets lost on average 0.91 kg more than people on low-fat diets after a year or longer. Triglycerides fell more (−0.18 mmol/L) and HDL "good" cholesterol rose more (+0.09 mmol/L), but LDL cholesterol also rose more (+0.12 mmol/L). The authors noted the weight difference was statistically real but small in practical terms.

Hall et al., 2016 — American Journal of Clinical Nutrition
Tightly controlled metabolic-ward studyn = 17 men4 weeks + 4 weeks

When calories were kept identical, switching to keto did not speed up fat loss. Body-fat loss actually slowed during the first two weeks of keto. Energy expenditure rose slightly (about 57 kcal a day).

Hall et al., 2021 — Nature Medicine
Randomised crossover, inpatientn = 202 weeks on each diet

With unlimited access to food, people ate about 689 kcal a day less on a plant-based low-fat diet than on an animal-based keto diet. This challenges the idea that keto automatically curbs appetite for everyone.

Takeaway: keto helps people lose weight mainly by making it easier for some people to eat less. Many find it very filling. Over the long term, results are similar to other diets. The best diet is the one you can stick with.
Goldenberg et al., 2021 — BMJ
Meta-analysis of 23 randomised trialsn = 1,3576 and 12 months

At 6 months, low-carb diets led to about 32 more people out of every 100 reaching diabetes remission (HbA1c under 6.5%) than control diets. They also gave about 3.5 kg more weight loss. By 12 months the benefits had largely faded, and there were signs LDL cholesterol worsened. Certainty was moderate to low.

Hallberg et al., 2018 — Diabetes Therapy (Virta Health trial)
Non-randomised controlled trialn = 262 keto + 87 usual care1 year

With intensive remote coaching and doctor-led medication changes, average HbA1c fell from 7.6% to 6.3% and weight dropped by 13.8 kg (about 12%). Insulin was reduced or stopped in 94% of users, and 83% were still in the program at one year. Triglycerides fell 24%, but LDL rose 10%. The usual-care group didn't change.

Gardner et al., 2022 — American Journal of Clinical Nutrition (Keto-Med trial)
Randomised crossover trialn = 33 completed (40 enrolled)12 weeks on each diet

In people with prediabetes or type 2 diabetes, HbA1c improved on both keto (−9%) and a Mediterranean diet (−7%), with no significant difference. Keto lowered triglycerides more but raised LDL by 10% (the Mediterranean diet lowered it by 5%). Keto was lower in fibre, vitamin C, folate and magnesium, and people found the Mediterranean diet easier to keep up afterwards.

Takeaway: keto can dramatically improve blood sugar, and many people cut their medication. But the medication changes must be managed by a doctor, and a lower-carb Mediterranean-style diet may do almost as well for some people.
Soto-Mota et al., 2024 — American Journal of Clinical Nutrition
Meta-analysis of 41 trialsn = 1,379

How much LDL changed on low-carb diets depended strongly on body size. In people with a healthy BMI (under 25), LDL rose by about 1.1 mmol/L on average. In people with a BMI of 35 or more, LDL actually fell slightly (about 0.2 mmol/L).

Across the trials above, the pattern is consistent: triglycerides fall and HDL rises, which are good changes. LDL often rises, sometimes a lot. Scientists still debate what a keto-driven LDL rise means for long-term heart risk, and no long-term trials have settled it.

Takeaway: get a cholesterol test before you start and again after about 3 months. That goes double if you're already slim, or have a family history of high cholesterol or heart disease.
Burke et al., 2017 — Journal of Physiology (replicated 2020, PLOS One)
Controlled training studiesElite race walkers (26 recruited in the 2020 repeat)About 3.5 weeks

Keto more than doubled how much fat the athletes burned during exercise (0.58 to 1.38 g per minute). But it made them less efficient at race pace and cancelled out the benefit of their hard training. In the 2020 repeat, the keto group was about 2.3% slower over 10 km, while the carb-fed groups improved.

Takeaway: expect workouts to feel harder for the first 2–4 weeks while your body adapts. Walking, weights and steady exercise are fine. If you race or do lots of high-intensity work, keto may hold you back.
Sethi et al., 2024 — Psychiatry Research (Stanford)
Pilot study, no control groupn = 21 (bipolar disorder or schizophrenia)4 months

Alongside their usual treatment, participants who followed keto saw metabolic syndrome drop from 29% of the group to none. They lost about 10% of their body weight, and their psychiatric ratings improved by 31% on average. Those who stuck to the diet most closely improved the most.

Takeaway: interesting and being actively researched, but far from proven. Keto must never replace psychiatric medication, and should only be tried alongside your treating team. Diet changes can alter the levels of some medicines, such as lithium.
Acharya et al., 2021 — Diseases
Meta-analysis of 36 studiesn = 2,795Average 3.7 years

5.9% of people on ketogenic diets developed kidney stones (7.9% of adults), much higher than the roughly 0.3% a year seen in the general population. About half were uric-acid stones.

Very few randomised trials run longer than 1–2 years, so the long-term effects of keto on heart disease, bone health and lifespan aren't known. Most of what we know about multi-year keto comes from children with epilepsy under close medical care.

Takeaway: drink plenty of water, get your bloods checked periodically, and keep eating plenty of vegetables. See the Safety & kit section.

The bottom line

  • Keto is a proven medical therapy for epilepsy and can powerfully improve blood sugar and type 2 diabetes, especially in the first 6–12 months.
  • For weight loss it works about as well as other diets over the long run. It suits people who find it filling and easy to stick to.
  • The main trade-offs are a possible rise in LDL cholesterol, lower fibre and some vitamins if it's done poorly, and a small but real kidney stone risk.
  • Do it well: lots of non-starchy vegetables, quality proteins and fats, enough salt and water, and blood tests before and after 3 months.

References

  1. Neal EG et al. The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial. Lancet Neurol 2008;7:500–6.
  2. Martin-McGill KJ et al. Ketogenic diets for drug-resistant epilepsy. Cochrane Database Syst Rev 2020.
  3. Bueno NB et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr 2013;110:1178–87.
  4. Hall KD et al. Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Am J Clin Nutr 2016;104:324–33.
  5. Hall KD et al. Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake. Nat Med 2021;27:344–53.
  6. Goldenberg JZ et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission. BMJ 2021;372:m4743.
  7. Hallberg SJ et al. Effectiveness and safety of a novel care model for the management of type 2 diabetes at 1 year. Diabetes Ther 2018;9:583–612.
  8. Gardner CD et al. Effect of a ketogenic diet versus Mediterranean diet on glycated hemoglobin in individuals with prediabetes and type 2 diabetes mellitus: the Keto-Med randomized crossover trial. Am J Clin Nutr 2022;116:640–52.
  9. Soto-Mota A et al. Increased low-density lipoprotein cholesterol on a low-carbohydrate diet in adults with normal but not high body weight: a meta-analysis. Am J Clin Nutr 2024.
  10. Burke LM et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol 2017;595:2785–807; and Burke LM et al. PLOS One 2020;15:e0234027.
  11. Sethi S et al. Ketogenic diet intervention on metabolic and psychiatric health in bipolar and schizophrenia: a pilot trial. Psychiatry Res 2024;335:115866.
  12. Acharya P et al. Incidence and characteristics of kidney stones in patients on ketogenic diet: a systematic review and meta-analysis. Diseases 2021;9:39.

Frequently Asked Questions

Most people get into ketosis at under about 20–50 g of net carbs a day. Starting at 20–30 g makes it very likely you'll get there. Some people can later go higher and stay in ketosis, which a blood ketone meter will show you. Get most of your carbs from non-starchy vegetables.

Keto is moderate in protein, not low. Well-formulated keto programs commonly aim for roughly 1.2–1.7 g of protein per kg of healthy body weight a day. Too little protein risks losing muscle, especially while you're losing weight. Our Protein Tracker can help you hit a target.

The only reliable way is a blood ketone test. A reading of 0.5–3.0 mmol/L is usually called nutritional ketosis. Signs like less hunger, "keto breath" or more frequent urination hint at it, but they aren't reliable. Urine strips work in the first few weeks, then often under-read.

No. Nutritional ketosis usually sits between 0.5 and 3 mmol/L with normal blood sugar and normal blood acidity. Ketoacidosis is a medical emergency with very high ketones that make the blood acidic. It mostly happens in people with type 1 diabetes, people taking SGLT2-inhibitor medicines, or in rare cases during breastfeeding or with heavy alcohol use. If you feel very unwell (vomiting, stomach pain, fast breathing, confusion), get medical help immediately.

Spirits have no carbs, and dry wine has about 2–4 g a glass, so they fit technically. But your body burns off alcohol before anything else, many people feel it more strongly in ketosis, and it lowers your willpower around food. Keep it occasional and avoid sugary mixers and beer.

Not necessarily. Many people use strict keto for a few months, then move to a more relaxed low-carb or Mediterranean-style way of eating to maintain their results. Long-term keto trials are limited, so if you stay on it for the long haul, keep up regular blood tests with your GP.

iPhone: open this page in Safari, tap Share, then "Add to Home Screen". Android: open it in Chrome, tap ⋮, then "Add to Home screen". It gets its own icon, and your ticked foods and shopping list are remembered on that phone.

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Disclaimer: This guide is general information based on published research. It is not medical advice and doesn't replace advice from your GP, specialist or an Accredited Practising Dietitian. A ketogenic diet can interact with medicines and health conditions. Talk to your doctor before starting, especially if you take medication for diabetes or blood pressure, or have any of the conditions listed in the Safety section. Nutrition values are estimates.